TY - JOUR A1 - Jensen, S. A. A1 - Rosu, Dana Maria A1 - Hertwig, Andreas A1 - Hansen, P.-E. T1 - Use of Rayleigh-Rice Theory for Analysis of Ellipsometry Data on Rough CIGS Films N2 - Ellipsometry is a useful tool for studying the optical properties of thin films such as photovoltaic devices. We employ Müller matrix ellipsometry to study the thin film photovoltaic material copper indium gallium selenide Cu(In,Ga) Se2 (CIGS), a commercially relevant material with high energy conversion efficiency. Confocal microscopy reveals an rms roughness of 68 nm, which greatly affects the ellipsometry data. Rayleigh-Rice theory is employed to account for the optical properties of the surface roughness in the ellipsometry experiment, and a library search method is used to compare Müller parameters calculated for various CIGS compositions, to the measured data. The Müller parameters calculated with the Rayleigh-Rice model are found to correspond well with the measured data, and a surface roughness of 37nm and a correlation length of 125nm are extracted. KW - Photovoltaics KW - Thin Films KW - Ellipsometry KW - Scattering Theory KW - Optical Wavefield KW - Simulation KW - Müller Polarimetry KW - Multidimensional Spectroscopy PY - 2017 DO - https://doi.org/10.1002/pssc.201700217 SN - 1862-6351 VL - 14 IS - 12 SP - 1700217, 1 EP - 5 PB - WILEY-VCH Verlag GmbH & Co. KGaA CY - Weinheim AN - OPUS4-43390 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pourjamal, S. A1 - Mäntynen, H. A1 - Jaanson, P. A1 - Rosu, Dana Maria A1 - Hertwig, Andreas A1 - Manoocheri, F. A1 - Ikonen, E. T1 - Characterization of thin-film thickness N2 - Analysis methods and instrumentation for obtaining optical parameters and thickness profiles of thin-film samples from spectrophotometric and ellipsometric measurements are presented. Measured samples include thermally grown and evaporated SiO2 on a silicon substrate and a polymer photoresist layer on silicon. Experimental results at multiple sample positions give the thickness uniformity and optical constants of thin films. The thickness results obtained with spectrophotometry and ellipsometry agree within 1 nm for the 300 nm thick layer of SiO2 on silicon. For the 1600 nm thick resist sample the agreement of the measurement methods is within 8 nm. For the sample with a nominally 6000 nm thick layer of SiO2 on silicon, there is a deviation of ~100 nm between the spectrophotometry and ellipsometry results. As an application, the optical parameters of a SiO2 layer on an induced junction silicon photodiode are determined by spectrophotometry and are used to confirm earlier values and uncertainties of the SiO2 refractive index and layer thickness non-uniformity. KW - Index of refraction KW - Thin-film thickness KW - Silicon dioxide KW - Spectrophotometry KW - Ellipsometry KW - Silicon photodiode PY - 2014 DO - https://doi.org/10.1088/0026-1394/51/6/S302 SN - 0026-1394 SN - 1681-7575 VL - 51 IS - 6 SP - S302 EP - S308 PB - Inst. of Physics Publ. CY - Bristol AN - OPUS4-32729 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rosu, Dana Maria A1 - Petrik, P. A1 - Rattmann, G. A1 - Schellenberger, M. A1 - Beck, Uwe A1 - Hertwig, Andreas T1 - Optical characterization of patterned thin films N2 - The present study investigates the use of imaging and mapping ellipsometry to determine the properties of non-ideal and patterned thin film samples. Samples which are candidates for future references and standards were prepared for this purpose. The samples investigated were lithographically patterned SiO2 and photoresist layers. The thickness and the optical constants of the two materials were determined using spectroscopic ellipsometry in the visible spectral range. On a larger lateral scale of several mm lateral resolution, the homogeneity was investigated using a goniospectral rotating compensator ellipsometer. A nulling imaging ellipsometer was used to determine the properties of the sample on a smaller scale of 25–150 µm. KW - Spectroscopic imaging and mapping ellipsometry KW - Inhomogeneous and patterned thin films KW - SiO2 KW - Photoresist KW - Ellipsometrie KW - Patterned films PY - 2014 DO - https://doi.org/10.1016/j.tsf.2013.11.052 SN - 0040-6090 VL - 571 IS - 3 SP - 601 EP - 604 PB - Elsevier CY - Amsterdam AN - OPUS4-32695 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rosu, Dana Maria A1 - Hertwig, Andreas A1 - Fleischmann, C. A1 - Tait, J. A1 - Beck, Uwe T1 - Optical investigations of PCDTBT-PC70BM blends for organic photovoltaics T2 - 9th Workshop Ellipsometry CY - Enschede, the Netherlands DA - 2015-02-23 PY - 2015 AN - OPUS4-32940 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rosu, Dana Maria A1 - Hertwig, Andreas A1 - Fleischmann, C. A1 - Tait, J. A1 - Beck, Uwe T1 - Optical characterization of PCDTBT-PC70BM bulk heterojunctions T2 - EMRS 2015 Spring Meeting CY - Lille, France DA - 2015-05-11 PY - 2015 AN - OPUS4-32942 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rosu, Dana-Maria A1 - Hertwig, Andreas A1 - Beck, Uwe A1 - Rotella, H. A1 - Nolot, E. T1 - Optical investigation of ZnO and doped ZnO thin films N2 - In the search for highly efficient, low-cost, non-toxic, transparent conductive oxides (TCOs) suitable for large area applications for photovoltaics, ZnO and ZnO-related materials have received considerable attention. In the present work, Al and Ga doped ZnO films on oxidized Si substrates are characterized using mainly variable angle spectroscopic ellipsometry; additional optical and non-optical techniques were employed to confirm and support the ellipsometric models considered. The samples were obtained by means of pulsed chemical vacuum deposition (CVD) and atomic layer deposition (ALD). As known from previous studies the presence of dopants in ZnO thin films generally induce significant changes in the optical, electrical and morphological properties. We present our findings for a series of Al and Ga doped ZnO layers with different concentrations of the dopants, discussing their influence on the optical and electrical properties. T2 - 7th International Conference on Spectroscopic Ellipsometry (ICSE-7) CY - Berlin, Germany DA - 06.06.2016 KW - doped ZnO KW - ellipsometry KW - optical properties KW - transparent conducting oxide PY - 2016 AN - OPUS4-37135 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rosu, Dana Maria A1 - Hertwig, Andreas A1 - Beck, Uwe A1 - Mäntynen, H. A1 - Manoocheri, F. A1 - Rattmann, G. A1 - Schellenberger, M. A1 - Petric, P. T1 - Optical Characterization of Highly Inhomogeneous Thin Films T2 - E-MRS 2013 Spring Meeting CY - Strasbourg, France DA - 2013-05-27 PY - 2013 AN - OPUS4-28805 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rosu, Dana Maria A1 - Hertwig, Andreas A1 - Beck, Uwe A1 - Petrik, P. T1 - Optical characterization of highly inhomogeneous thin films T2 - 8th Workshop Ellipsometry CY - Dresden, Germany DA - 2014-03-10 PY - 2014 AN - OPUS4-30116 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rosu, Dana Maria A1 - Hertwig, Andreas A1 - Petrik, P. A1 - Beck, Uwe T1 - Optical characterization of non-ideal samples T2 - E-MRS 2014 SPRING MEETING CY - Lille, France DA - 2014-05-26 PY - 2014 AN - OPUS4-30117 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rosu, Dana Maria A1 - Hertwig, Andreas A1 - Beck, Uwe T1 - Thin layers deposited with plasma sputtering and e-beam evaporation as reference samples for thickness determination by spectroscopic ellipsometry T2 - 14th International Conference on Plasma Surface Engineering (PSE) CY - Garmisch-Partenkirchen, Germany DA - 2014-09-15 PY - 2014 AN - OPUS4-31497 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rosu, Dana-Maria A1 - Hertwig, Andreas A1 - Beck, Uwe T1 - The accuracy and reproducibility in thickness determination of thin films using SE N2 - Maintaining a consistent product quality is critical for the thin film industry. Therefore, the development of highly accurate protocols able to detect variations and nonidealities in manufactured thin film devices is essential and helps improve production quality and decrease manufacturing costs. The present work will discuss the accuracy and reproducibility in the determination of the thickness of thin films relevant for optoelectronic industry using spectroscopic ellipsometry, starting with the importance of set-up calibration, the need for very well defined calibration standards suitable for real devices and not least, the importance of accurate data analysis. As ellipsometry is an indirect method and theoretical modelling is needed to obtain the desired information regarding the investigated samples (e.g. thickness, roughness, optical constants), the model uncertainty has to be discussed and taken into account. If for ideal samples consisting of single layers with well-known optical constants the determination of thickness and roughness is straight forward and pretty accurate, for real samples, more complex theoretical models are needed and extracting accurate information regarding the samples can be very challenging. With careful calibration and a multidisciplinary approach, a combined measurement methodology can be developed enabling reliability, comparability, and accuracy. For production-relevant operation, maintaining the ease of use and scalability of ellipsometry as a technique can also be retained. T2 - EOSAM (European Optical Society Annual Meeting) CY - Berlin, Germany DA - 26.09.2016 KW - Spectroscopic ellipsometry KW - Thin films KW - Film thickness determination KW - Uncertainty PY - 2016 AN - OPUS4-38109 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rosu, Dana Maria A1 - Hertwig, Andreas A1 - Beck, Uwe A1 - Stockmann, Jörg M. T1 - Spektrale und Imaging-Ellipsometrie von Graphen-Proben der TUW und des IHP T2 - 6. Graphen-Meeting CY - Berlin, Germany DA - 2015-11-06 PY - 2015 AN - OPUS4-35209 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rosu, Dana-Maria A1 - Ortel, Erik A1 - Hodoroaba, Vasile-Dan A1 - Kraehnert, R. A1 - Hertwig, Andreas ED - Hertwig, Andreas ED - Hinrichs, K. ED - Beck, Uwe ED - Esser, N. T1 - Ellipsometric porosimetry on pore-controlled TiO2 layers N2 - The practical performance of surface coatings in applications like catalysis, water splitting or batteries depends critically on the coating materials’ porosity. Determining the porosity in a fast and nondestructive way is still an unsolved problem for industrial thin-films technology. As a contribution to calibrated, non-destructive, optical layer characterisation, we present a multi-method comparison study on porous TiO2 films deposited by sol-gel synthesis on Si wafers. The ellipsometric data were collected on a range of samples with different TiO2 layer thickness and different porosity values. These samples were produced by templated sol-gel synthesis resulting in layers with a well-defined pore size and pore density. The ellipsometry measurement data were analysed by means of a Bruggeman effective medium approximation (BEMA), with the aim to determine the mixture ratio of void and matrix material by a multi-sample analysis strategy. This analysis yielded porosities and layer thicknesses for all samples as well as the dielectric function for the matrix material. Following the idea of multi-method techniques in metrology, the data was referenced to imaging by electron microscopy (SEM) and to a new EPMA (electron probe microanalysis) porosity approach for thin film analysis. This work might lead to a better metrological understanding of optical porosimetry and also to better-qualified characterisation methods for nano-porous layer systems. 1. IntroductionPorous materials, especially porous thin films play an importantrole in chemical and physical technology in every case where thecontact area between two media has to be maximised. From cataly-sis to photochemistry and photovoltaics, the applications of porouslayer materials are diverse and numerous [1–6].The accurate and non-destructive characterisation of porousfilms for layered systems poses a challenge. This applies especiallyfor the key parameter of porous films, their porosity, i.e. the mix-ing ratio between the Matrix of the film (host material) and thepore volume which is empty or filled with a fluid medium (inclu-sions). This parameter influences most of the physical and chemicalproperties of a porous thin film and is therefore essential for theunderstanding as well as the optimisation of this class of materials. T2 - International Conference on Spectroscopic Ellipsometry (ICSE-7) CY - Berlin, Germany DA - 06.06.2016 KW - Spectroscopic ellipsometry KW - Porous materials KW - Porosimetry KW - Multi-sample analysis KW - Thin film metrology PY - 2017 DO - https://doi.org/10.1016/j.apsusc.2016.11.055 SN - 0169-4332 SN - 1873-5584 VL - 421 IS - Part B SP - 487 EP - 493 PB - Elsevier B.V. AN - OPUS4-42517 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -